1. Field of Invention
This relates generally to the field of portable consumer electronics devices and peripherals thereof, and in one exemplary enables a user device such as a portable media player to dynamically adapt to a wide variety of accessory devices.
2. Description of Related Technology
Portable media players (such as the Apple iPod™ family of devices and other so-called “MP3 players”), cellular telephones/smart phones (such as the Apple iPhone™), handheld computers, and personal digital assistants (PDA) allow users to store and playback audio and video files. Such devices have become extraordinarily popular, and their use has greatly enhanced the quality of life for many people. However, as the use of such equipment has increased, so has the need to connect equipment of differing types and functions purchased from different manufacturers. For example, an iPhone and a digital camera may each be useful when used alone; however, the ability to connect the digital camera to the iPhone and exchange information (e.g., photos, video) between the two makes the combination even more useful and flexible.
Connection of USB Devices to Connectors
FIG. 2 illustrates a typical prior art user device configuration, wherein a user device such as a portable media player or smartphone 200 is connected via a multi-pin connector to a USB Type A connector receptacle 202 (e.g., Camera Connector “dongle”). A USB-enabled camera 204 is then connected to the receptacle via an interface cable 206 between the devices. The illustrated receptacle 202 comprises for instance a microcontroller unit (MCU; not shown), a serial interface, FireWire (IEEE Std. 1394a-c) interface, plus device authentication capability, and provides a USB pass-through capability to the USB cable, as well as a 5V DC/DC step-up PSU. The illustrated receptacle device 202 authenticates the connected media player or smartphone 200 over the serial pins, and a signal sent over the serial pins tells the user device 200 to enter a USB host mode, with USB signal “pass through” to/from the peripheral for transferring data over the interface.
In this instance, the media player, smartphone or other device operates as a USB host at all times, based on an active signal from the receptacle 202. The MCU does not communicate with the user device 200 over the USB interface. Rather, only traditional USB-based speed detection and identification mechanisms (i.e., those of FIG. 1 based on D+ and D− pins) are employed within the receptacle 202 when the USB camera 204 is plugged into the receptacle 202. The receptacle power “booster” is used to boost the 3.3V output of the user device 200 to 5V, thereby signaling the connected camera 204 that the device to which it is connected is acting as a USB host, in response to which the camera 204 configures it D+/D− USB signals accordingly.
Separate hardware or other apparatus are required to permit interfacing of USB-based devices. For instance, in the extant “host mode” configuration of FIG. 2, a separate receptacle 202 (e.g., the Apple iPod Camera Connector dongle) having significant intelligence and complexity is required in order to permit the slave device (USB camera) to transfer media to the host media device or smartphone. This is less than optimal, in that it requires the user to possess such a complex dongle 202, which is generally only suited to interfacing a single type of device (here, a USB camera).
Also, under the scheme shown in FIG. 2, digital audio output from the media player or smartphone is precluded, in that digital audio cannot be output without the peripheral acting as a USB host. Accordingly, the connection of digital audio-consuming peripheral or accessory devices such as speakers is frustrated using the “dongle” approach of FIG. 2, since the media player or smartphone always acts as the USB host in such configurations. Moreover, even when using other approaches that may not automatically place the user device into USB “host” mode, the peripheral device must necessarily be able to act as a host, thereby requiring a greater degree of complexity and cost in the accessory. There is currently a significant market for lower-end (i.e., simpler and lower cost) digital audio accessories; this market cannot be fully realized or leveraged by the prior art solutions described above.
Therefore, improved methods and apparatus are needed to support maintaining all of the desired functionality of the electrical and signal interface(s) supported therein, and providing the ability to selectively negotiate operation according to various modes of functionality and or connectivity. Enhanced detection schemes are needed to differentiate between connectors supporting newer functionality, and connectors which retain legacy characteristics. Ideally, such detection schemes would enable present and future feature support and expansion capability, while retaining backward compatibility. For example, devices which were previously limited to peripheral or “slave” device operation would be newly suitable for operation as a “host” device under appropriate conditions, and intelligent selection between the two would be enabled as well. Lastly, such improved methods and apparatus should support a broad population of accessory devices.